Induction heating work-holding means



March 24, 195 3 E. M. WHARFF, JR I 2,632,841

INDUCTION HEATING WORK-HOLDING MEANS Filed Sept. 9, 1949 lNVENTOR Ed vyord M.Whorff,Jr.

' ATTORNEY WITNESSES:

Patented Mar. 24, 1953 INDUCTION HEATING WORK-HOLDING MEANS Edward M. Wharff, Jr., Ellicott City, Md., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 9, 1949, Serial No. 114,753

Claims.

My invention generally relates to induction heating of the inner and outer surfaces of hollow workpieces. More particularly my invention relates to improved fixture means for heat-treating the inner and outer surface portions of a hollow object or part such as, for example, a sleeve, bushing or hollow shaft.

Objects of my invention are to provide a fixture in which a hollow object can have its entire inner surface or its entire outer surface, or both, inductively heat-treated; to provide a fixture of a type described which can be used in situ or on a conveyor system such as, for example, an indexing turntable, for heat-treating objects in the manner as aforesaid and on a large scale; to provide a fixture of a type described which reduces manual handling of the objects to a minimum and to provide a fixture of a type described which is rugged and simple in construction and eflicient in operation.

In accordance with specific aspects of my invention. a single workpiece is held by a fixture comprising two vertical nested or concentric work-carrying members which are separately axially relatively movable with respect to each other. The fixture-members are successively raised and lowered. As one of the fixture-members moves through its movement-cycle, it carries the workpiece into heating relation with an inductor, or induction-heating'coil, which heats the outside of the workpiece. As the other'fixture-mem'oer moves through its movement-cycle, it carries the workpiece into heating relation with a second inductor for heating the inside. Preferably the work-carrying fixture-members are rotated as each is independently moved axially.

For greater. utility, each work-carrying fixture member can be provided with adapter portions which enables it to be used with workpieces of different diameters.

Objects, features, and innovations of my inven.

tion. in addition to the foregoing, will be discernible from the following description of preferred embodiments. The description is to be taken in conjunction with the accompanying drawing. The drawing is not to scale and omits details that are not believed to be necessary for understanding of the invention by one skilled in the art. In the drawing:

Figure l is a sketchy plan view of a turntable adapted to receive a plurality of work-holding fixture-means, in accordance with my invention;

Fig. 2 is a vertical sectional view through the axis of a work-holding fixture carried by the turntable;

Fig. 3 is a partial sectional view showing the inner fixture-member in a raised position in which the outer surface of a workpiece can be heat-treated; I

Fig. 4 is a partial sectional view of the upper part of a work-holding fixture along the lines of Fig. 2 but having different work-carrying adapter portions associated therewith; and

Fig. 5 is a partial elevational view of amodified application of my invention.

Referring more particularly to Figs. 1-3, a turntable I is indexed, or intermittently driven step-by-step, by a drive that includes gearing 2 and an electric motor 3 controlled in any suitable manner. The turntable 1 comprises a tabledisc 4 having an outer edge 5 and a plurality of equally spaced holes 6. A work-holding fixture, indicated in its entirety by the reference number l, is placed in each of the holes 6. The indexed turntable moves the fixtures successively to a position or work-treating station point A where the turntable remains stationary for any desired time. A suitable heat-treating means and suitable fixture-operating means to be later described are located at the station point A. A workpiece W in the form of a bushing or tubular member is placed in each fixture before it reaches the station point A, and removed therefrom preferably after it leaves such point.

In the embodiments described the fixtures associated with the turntable are alike, except for their adapters, and a description of a single one that is at the work-treating station point A should suffice for all. As indicated in Fig. 2, each work-holding fixture l is carried in an upper bearing 8 and a lower bearing 9. The upper bearing 8 is carried by the table-disc 4 of the turntable I; and the lower bearing '9 is carried by an arm member If} fastened to but spaced from the bottom of the table-disc 4. The upper bearing '8 is a guide bearing provided with upper and lower thrust faces; and the lower bearing "9 is a guide bearing provided with an upper thrust surface. [It is to be understood that there are as many pairs of bearings 8 and '9, carried by the table-disc 4, as there are fixtures for the turntable.

Each fixture also comprises an outer fixturemember II in the form of a tubular or hollow cylindrical member which rotatably fits the bearings 8 and 9 and is provided with an upper flange l2, adapted to rest on the upper bearing 8, and with a lower disc-like base I3. The outer fixturemember H has an elongated axially-extending slot or keyway M which slidably receives a key l5 fixed to a rotatable gear in the form of an 3 angular friction disc IS. The gear or disc I6 is concentrically around the outer fixture-member II and is rotatably held in place by the tabledisc A and the associated arm I0.

Each fixture I also comprises an inner fixturemember 2i slidably nested inside the outer fixture-member II. The inner fixture-member 26 is in the form of a solid shaft which is about twice as long as the outer fixture-member H, and has its lower portion provided with an elongated axially-extending slot or key-way 22 that receives a key 23 fixed to the inside of the outer fixturemember II. This key 23 also serves as a stop to keep the inner fixture-member 2I from dropping below the position shown in Fig. 2.

The upper parts of the outer and inner fixture-members II and 2I removably receive adapter portions 24 and 25, respectively; The adapters are shaped to accommodate the internal and external diameters of the particular workpiece being heat-treated; and by changing adapters, each fixture can heat-treat different shapes of workpieces.

In general, the top of the outer adapterportion 24 is .provided with a suitable round seat 26 in which the workpiece removably rests. The bottom of the outer adapter 24 comprises a lower portion shaped to fit a seat in the top of the outer fixture-member I I. Properly placed holding pins 21 may be provided in the outer adapter, that fit correspondingly placed holes in the fixture-member II for keeping the adapter in fixed relation with respect to the fixture-member. The outer adapter 24 has an internal diameter which is larger than the diameter of the bore or internal hole in the workpiece W, and larger than the external diameter of the inner fixture-member 2 I.

The inner adapter portion comprises a stud having a head 23 and a narrower polygonal stem which removably fits into a suitable central hole in the top of the inner fixture-member 2 I. The adapter-head 28 has a maximum diameter which is less than that of the bore of the workpiece W Preferably the head-diameter is less than that of the inner fixture-member 2| so as to provide a round seat 29 for receiving the workpiece when the inner fixture-member is raised, as shown in Fig. '3.

The heating means at the work-treating station point A comprises a pair of inductors for externally and internally heating the workpiece W. The inductors are mounted in any suitable way so as to be coaxial with the fixture-members II and 2| when the last are at the station point A. The inductors comprise an outer or larger inductor 34 and an inner or smaller inductor 35.

Quench rings 36 and 31, fed from water pipes 38 and 39, respectively, are provided at the bottom of the inductors 34 and 35, respectively. Preferably, the outer fixture-member II is provided with one or more full length drain slots or holes 40 axially along its inner surface, through which quench water may drain. Preferably, one of the inductors, shown as the outer inductor 34, is stationary, and the other inductor is rectilinearly controllably reciprocable, as indicated by the double headed arrow BB.

Preferably, in normal position of the fixturemembers II and 2I, as shown in Fig. 2, the top of the head 28 of the inner fixture-member 2I is spaced from the bottom of the seat 25 of the outer fixture-member I I. The spacing allows for free movement of the inner inductor 35 through the bore of the workpiece.

The outer inductor 34 comprises a helical coil of tubular material, the coil having an inner diameter slightly larger than the outer diameter of the workpiece W. The outer inductor has energy-supplying conductors 4| that extend radially outward from the turns of the inductor and can be connected to any suitable source of high-frequency energy. The inner inductor 35 is coaxial with the outer inductor 34 and has an outer diameter which is slightly less than the diameter of the bore of the workpiece W. The inner inductor 35 has energy-supplying conductors 42 that can be connected to any suitable source of highfrequency energy. The inner conductor 42 and pipe 39 extend upwardly through the inside of the turns of the inner inductor 35.

The fixture-operating means at the work-treating station point A comprises a rotating disc 43 on which the friction disc I6 rides as the latter moves into its resting place at the work-treating station point A. The fixture-operating means, also comprises a raising means 44 for the outer fixture-member II, and a raising means M for the inner fixture-member 2|. Each raising means comprises a pneumatically raisable and lowerable piston or rod 45 having a top formed of a ball rotatably held in place. Each raising means can be controlled in any suitable manner, preferably by an automatic timing means. A control of any desired kind is schematically rep resented by valves 46 and 41, respectively, for controlling the reciprocation of the piston.

An important advantage of the apparatus described resides in the many different ways in which it can be operated, several, but not all, of which are described below.

Assume that a workpiece W is placed in the outer adapter portion 24 of a fixture l of the turntable I, at a point before the heat-treatin station point A, and that this fixture subsequently is moved by the turntable to the work-treating station point A, where it remains for a time. The workpiece will then be directly below the inductors 34 and 35.

For heat-treating the internal surface of the workpiece, the inner inductor 35 can be energized and lowered to scan the internal surface.

Instead of heating the internal surface of the workpiece W as the inner inductor 35 is lowered, the heating can be carried out while the inductor 35 is raised, after being fully lowered. For such operation, the deenergized inductor 35 is lowered to a point at or below the bottom of the workpiece. As the inductor 35 rises from such point it is energized to heat the inner surface of the workpiece. Quench liquid can be simultaneously supplied to the inner quench ring 31. Obviously, by suitable control of the energization of the inductor 35, the full length of the internal bore of the workpiece or desired parts thereof can be treated.

In the foregoing processes, the inductor 35 alone is moved for heating the bore of the workpiece. However, the raising means 44 may be activated to raise the outer fixture-member Ii at the same time that the inductor 35 is energized and lowered. After the heating, the

quench ring 31 can be supplied with quenching liquid. Preferably, however, for this mode of operation, the quench ring 31 should be located above the inductor 35.

By controlling the speed of operation of the raising means 44 for the outer fixture-member I I in conjunction with the reciprocation of the inner inductor 35, the power input to the internal surface ofthe workpiece can be varied without changing the speed of movement of the inductor or the power delivery of the high-frequency supply to the inductor. 1 l

It is also possible to heat-scan the internal or inner surface of the workpiece while the in-. ductor. 35. is stationary in a proper .location. Thus, with the parts as shown in Fig. 2, the inner inductor can be lowered so that its bottom is at the line CC. It is then hold stationary and the raising means 44 activated to move the workpiece W past the inductor 35 which is" suitably, energized during such movementofthe workpiece. The lineCC must be adequately 'be-. low the combination of an outer quench ring .36 and outerinductor 34 .to permit a full heating movement of the workpiece without havingthe top of the outer adapter portion 24 hit or contact such combination. Y Ii After the inner surface has been heattreated-, the-various parts canbe restored to the positions shown .iniFig.I2, but, if desired, the inner inductor 35 can be raised higher. The'apparatus is then. ready for operations to heat-treat. the external surface of theworkpiece. To thisiend, the raising means 44' is activated to move its piston 45 upwardly. Because of the slot'and key arrangement 22; .and'23," only the inner fixturemember 2! rises? Asithe head 28 of the adapter portion 25 of the inner fixture-member l l passes into the bore ofthe workpiece, the workpiece seats in the seat 29 of the :inner fixture-member, and islifted from theqadapter portion 24 of the outer fixture-member ll; As the inner fixture member H continues to rise, it moves the workpieceinto'th'ei outer inductor 34, whereupon the outer inductor is energized for heating the outer surface of the workpiece. After the heating, the supply of energy to the inductor 34 is cut offythe. raisin means activated to lower the inner fixture-member 2|, and water or other liquid supplied to the outer quench ring 35 for quenching the workpiece W as the inner fixturemember 2! drops.

During the time that the fixture is at the station point A, and the workpiece is being heattreated, the fixture disc 15 will be rotated by the rotating disc 43 of the fixture operating means. Because this fixture disc I6 is slidably keyed to the outer fixture-member H, and the outer fixture-member ii is slidably keyed to the inner fixture-member 2!, the two will rotate in unison,

regardless of the positionof either. Consequently.

the workpiece 'W will be rotated regardless, of which fixture-member carries it.

After the workpiece at thestation point A. is heat-treated internally and externally, the parts are restored to their positions as shown in .Fig.

2, and the indexing turntable moves the fixture.

with the heat-treated work to its next, stopping point. Suchmovement of the turntable places the next successive fixture at the station point A where the workpiece carried by this fixture is in position to be heat-treated.

My invention can be used for different sizes of workpieces by changing the form of the adapters, carried by the fixture-members l I and 2! respectively. Fig. 4 shows this expedient. .In Fig. 4 the outer fixture-member H carries an outer adapter portion 24 adapted to seat aworkpiece W having a larger outer diameter than the workpiece W. Similarly the inner fixture-member 21- carries an inner adapter portion 25 adapted to engage the workpiece W which, as shown, has

abore with an internal diameter which is smaller than that of the workpiece .W. v

In the embodiments shown in Figs. 1 and 12, the internal and externalsurfaces of thetwork piece W are heat-treated 'while the workpiece is at the single heat-treating station point A. However, the separate surfaces can be heattreated at separate stations in. the movement of the indexing turntable I. An embodiment of this kind is briefly shown in Fig. *5 where the tab1e-disc4 is shown with two successive workholding fixtures I, a first of which is at one worktrea-ting station point Biand the second of which is at a successive station point C. At the station point B theinner surface of aworkpiece is heat-treated; and at the station C point the outer'surface of a workpiece isheat-treated.

It is, of course, evident that suitable means are provided for controllingthe activation of the raising means 44 andM', for moving and controlling the movement of one orthe other of the inductors 34 and35, and for controlling the energization of the inductors 34and 35. Various forms of such means are well known, and, therefore, are not specifically part of my invention; but broadly are indicated respectively by the valves Hand 41, the arrow BB, and switches D. It is also evident that the normal positions of the fixture-members l l and 2| could be reversed, with the workpiece resting in the" inner fixture member, as indicated in Fig; 3.

While I have described my invention in forms which are now preferred, it 'is obvious that its principles can be embodied in other-forms and modifications.

I claim as my invention:

1. Induction heating means comprising, in combination, a work-holding fixture adapted to receive a workpiece having an outer surface and an inner surface defining a central opening, said fixture comprising a first fixture-member having seating means adapted to engage an outer portion of the workpiece and a second fixturemember having a seating means adapted to engage an inner portion of the workpiece, said fixture-members being nested, means for reciproeating one of said fixture-members, with respect to the other, a pair of inductors arranged to have substantially parallel axes, with the axis of a first inductor extending inside the second inductor, one of said inductors being arranged so that it is adapted to inductivelyheatsaid inner surface, and the other'of said inductors being arranged so that'it is adapted to inductively heat said outer surface, said first fixture member being movable along the axis of a first of said inductors and relative to said first inductor, and the second fixture member being movable along the axis of the second inductor second inductor. p

2-.-Induction heating means comprising, in combination a work-holding fixture adapted to and relative to the receive a workpiece having an-internal surfacedefining a central-opening, saidflxture comprising apair of nested fixture-members slidable withrespect to each other, a first of said fixture-members comprising seat-means for engaging an outer portion of the workpiece in a manner to leave the surface of its central opening. exposed, and asecond of said fixture-members comprising seat-means for engaging an inner portionpof the workpiece in a manner to leave an outer surface of theworkpiecevexposed, in-. ductor heating means for each of said surfaces,

and means foralternately moving in anaxial 7 direction eachof saidfixture-members.with respect to the other to place the respective surfaces of the workpiece into heating relation with said inductor heating means.

3. Induction heating means comprising, in combination, a work-holding fixture adapted to receive a workpiece having an internal surface defining a central opening, said fixture comprising a pair of fixture-members slidable with respect to each other, a first of said fixture-members comprising seat-means for engaging an outer portion of the workpiece in a manner to leave its central opening exposed, and a second of said fixture-members comprising seat-means for engaging. an inner portion of the workpiece in a manner to leave its outer surfare exposed, the seat-means of said first fixture member having a central opening axially positioned relative to the central opening of the workpiece, with the central opening of said seat-means being smaller than the central opening of said workpiece, and the seat-means of said second fixture member comprising a support member having an external dimension greater than the dimension of said workpiece central opening, an internal-sur face-heating inductor operatively associated with said first fixture-member, an external-surfaceheating inductor operatively associated with said second fixture-member, means for relatively moving said first fixture-memberand its associated inductor whereby the last said inductor is adapted to heat the workpiece at its internal surface, and means operated separately from the last said means for relatively moving saidsecond fixturemember and its associated inductor, whereby the last said inductor is adapted to heat the workpiece at its external surface.

4. A work-holding fixture of a type described for treating a workpiece having a central ope11- ing, comprising an outer work-carrying fixtrr member comprising a holiow'rod, an inner we carrying fixture-member comprising a rod having a portion slidable inside said'first fixturemember, each of said fixture-members comprising work-engaging means providing a work receiving seat, said seat of said outer fixturemember having a central opening axially posi tinned relative to the opening of the workpiece and having a diameter greater than the diameter of the workpiece opening, an inner diameter which is larger than the maximum'diameter "of said rod-portion of said innerfixture member, and said seat of said inner fixture-member hav ing a diameter which is less than that e'f said central opening of the workpiece.

Q A work-holding fixture of a type described for treating a workpiece having a central opening, comprising an outer work-carrying fixturemember comprising a hollow red, an inner workcarrying fixture-member comprising a rod having a portion slidable inside said first fixturemember, each of said fixture-members comprising work-engaging means providing a workreceiving seat, said seat of said outer fixturemember being annular and having an inner diameter which is larger than the maximum diameter of said rod-portion of said inner fixture member and larger than said central opening'of the workpiece, said seat of said inner fixturemember having a maximum diameter which is less than that of the central opening of said workpiece, a pair of inductors, a, first of said inductors having a diameter less than that of said hollow rod, and a second of said inductors having a diameter larger than said diameter of said seat of said outer fixture-member, said inductors being coaxial with said fixture-members, and operable means for separately relatively reciprocably moving each of said fixture-members with respect to said inductors.

6. A work-holding fixture of a type described for treating a workpiece having a central opening, comprising an outer work-carrying fixturemember comprising a hollow rod, an inner workcarrying fixture-member comprising a rod having a portion slidable inside said first fixturemember, each of said fixture-members comprising work-engaging means providing a workreceiving seat, said seat of said outer fixture member being annular and having an inner diameter which is larger than the maximum diameter of said rod-portion of said inner fixturemember and larger than said workpiece central opening, said seat of said inner fixture-member having a diameter which is less than'that of the internal opening of said workpiece, means for vertically and reciprocably supporting said outer fixture member, a pair of inductors above said fixture-members, reciprocating means engageable with said outer fixture-member for reciprocating it to bring the workpiece carried thereby into and out of a first oi said inductors, and different reciprocating means engageable with said inner fixture-member for reciprocating it inside said outer fixture-member for bringing the workpiece carried by said inner fixture-member into and out of the second of said inductors.

7. Means for successively heat-treating a plurality of workpieces, comprising, in combination, a conveyor having a plurality of spaced workholding fixtures; said conveyor being movable step-by-step so that each fixture is temporarily placed at a work-treating station point; each of said fixtures comprising a hollow outer fixturemember reciprocably carried by said conveyor. an annular member around said fixture-member rotatably carried by said conveyor, key and elongated-slot means between said annular member and fixture-member, an inner fixture-member slidably nested in said outer fixture-member, and key and elongated-slot means between said fixture-members; means at said station point for rotating said annular member; a pair of inductors above said conveyor; means for selectively reciprocating said fixturemembers forcausing the outer fixture-member to move a workpiece associated therewith into and out of a first of said inductors and for causing said inner fixture-member to move a workpiece associated therewith into and out of the second of said inductors.

8. Means for successively heat-treating a plurality of workpieces, comprising, in combination, a conveyor having a plurality of spaced workholding fixtures; said conveyor being movable step-by-step so that each fixture is temporarily placed at a plurality of work-treating station points; each of said fixtures comprising a hollow outer fixture-member reciprocably carried by said conveyor and an inner fixture-member slidably nested in said outer fixture-member; an inductor at a first and second of said station points, above said conveyor; means at a first-of said station points for relatively reciprocating said outer fixture-member into and out of operable association with a first of said inductors; and means at a second of said station points for relatively reciprocating said inner fixture-memher into and out of operable association with a second of said inductors.

and reciprocating 9. Means for successively heat-treating a plurality of workpieces, comprising, in combination, a conveyor having a plurality of spaced workholding fixtures, said conveyor being movable step-by-step so that each fixture is temporarily placed at a work-treating station point; each of said fixtures comprising a hollow outer fixturemember carried by said conveyor, an inner fixture-member relatively slidably nested in said outer fixture-member, a pair of inductors at said station point, and means at said station point for selectively alternately reciprocating said fixture-members into and out of operable relation with said inductors.

10. Means for successively heat-treating a plurality of workpieces each having a central opening, comprising, in combination, a conveyormeans having a plurality of spaced work-holding fixtures, said conveyor-means being movable step-by-step so that each of said fixtures is temporarily placed in a work-treating station point, an inductor means at said work-treating station point, each of said fixtures comprising a first fixture-member having a seating means adapted to engage an outer portion of the workpiece and a second fixture-member having a seating means adapted to engage an inner portion of the workpiece, and reciprocating means at said station point for selectively reciprocating the respective fixture-members into and out of operative association with said inductor means.

EDWARD M. WHARF'F. J R.

REFERENCES CITED The following references are of record in the file of this patent:

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